Abstract : The purpose of this reference manual is to make available to the USAF an unclassified, continuously maintainable handbook of the most current technology which can be employed in the design and acquisition of secure computer systems. This handbook is referred to as the Computer Security Technology Reference Manual (CSTRM) and is intended to provide a basis for evaluating and improving the security of existing USAF computer systems with emphasis on the hardware and software components of these systems. Although it may also serve as a source of computer security technology for the designers of future USAF computer systems, the Manual is intended primarily for those USAF personnel currently charged with the responsibility of establishing, maintaining and improving the security of existing computer systems.